A laser displacement sensor device repeatedly measures the intensity of laser light reflected from a measurement target and calculates displacement amounts of the target on the basis of the results of the measurements. The result of the measurement of the light intensity contains noise, and therefore the calculated displacement amount also contains noise. The noise contained in the displacement amount is found in the form of a variation in the displacement amount when the displacement amount of the same target is repeatedly measured. For this reason, the laser displacement sensor device calculates moving average of the calculated results of the displacement amounts to thereby obtain a displacement amount having the noise reduced. For the calculation of moving average, an arithmetic mean is continuously calculated for a time-series digital signal over a specific period of time, as described in Patent Literature 1, for example. For example, the laser displacement sensor device obtains a moving average by adding up 64 pieces of data and dividing the resultant sum by 64, and determines that the obtained moving average is a displacement amount of the measurement target.